Hot Water

HOT WATER: About 10% of a home’s energy use




It takes energy from your water heater to produce hot water, so saving water,
especially hot water, also saves energy.


The first obvious step is avoid running taps when not using them and make sure
all leaks or drips are fixed. A simple additional step is to install low-flow faucet
aerators (~$1) and shower-heads (~$10-15) that aerate water to reduce usage
while maintaining pressure. While a standard showerhead uses up to 5.5 gallons
of water per minute a low flow high pressure spray showerheads reduce that
figure to 1-1.75 gallons per minute without reducing water pressure. Similarly,
replace standard ~3 gallon per minute faucet aerators with 1-1.5 gallon per
minute aerators on sinks such as in the bathroom that you use to wash but not to
fill containers (such as in the kitchen) – filling pots, glasses, or other containers
takes significantly longer with an aerated faucet. Cutting hot water use by half
by installing low flow technology provides among the greatest returns per effort
investment, both from saved water and form saved heating fuel.


Dishwashers are also generally more efficient in terms of hot water than washing
dishes by hand, but you should wash full loads rather then just a few dishes at a
time in order to optimize energy savings.




Some tips for saving hot water and heating fuel when doing laundry:


  • Use cold wash and rinse settings unless your clothes are extremely soiled.
  • Presoak especially grubby, muddy clothes/ rags to protect the washing machines
  • Wash clothes in a small number of large loads.
  • High-efficiency washers work harder if too much soap is added – use the recommended amount, not more.
  • If you have a choice, use frontload washing machines – they use 38% less water and 58% less energy than top-loading washing machines (according to Friendly Plumber




120 degrees F is normally about the hottest you want your home water to
get (for bathing, rinsing, etc.), so set your hot water heater to 120 unless you
have a special reason for high heat. If it is set higher, you will waste energy
by overheating it and then having to add cold water to get it to a manageable
temperature. Going below 120 degrees F is unsafe for sanitation and bacteria


If sediments are accumulating at the bottom of your hot water tank, the machine
will have to work harder to heat the water, wasting energy. To addess this
potential problem open the drain valve to flush the tank while the heat is off and
then let the tank fill before turning back on.


If your hot water heater is warm to the touch, it means it is losing 25-40% of its heat (according to the American Council for an Energy Efficient Economy – To avoid this waste, wrap it in a insulating blanket designed specifically for hot water heaters – using a standard blanket or fiberglass batts can be dangerous. Use a measuring tape to identify the right size – you should be able to find insulated hot water heater blankets at most hardware stores for under $20.


Wrap at least the first 10 feet of the hot water pipe line from the water heater with
pipe wrap to prevent heat loss – you can tell which pipes need to be insulated by
simple touch (it will be hot). If you find that you need to run your faucets for a while before they are hot, this is an indicator that your pipes are losing heat between the hot water heater and the faucet. Insulating pipes will also prevent them from freezing or


You can install a timer to stop heating water at times when it will not be used
such as the middle of the day or the middle of the night – just be aware that some
timer models must be adjusted manually which requires a delay before using hot
water – others are programmable. You can also just shut the water heater off if no
one will be using hot water for long periods such as a vacation.




If your hot water heater is reaching the end of its life or you are ready to make an
investment in an upgrade, switch to a high efficiency unit or an on-demand hot
water heater, which heats water only as it is used rather than keeping a full tank
warm at all times. These units will cost slightly more but will pay for the extra in
energy savings within a few years.


Also consider switching to renewable hot water heating. You can temper cold
water with ground-source heating, but the primary renewable energy technology
for heating hot water is solar hot water heating. A number of solar hot water
technologies are available, and while they have substantial upfront cost, the
energy savings usually pays for itself in under ten years. Solar hot water panels
heat water based on the intensity of the sun, not the heat of the air, so they can
provide hot water even in the winter. However, due to the short days and low
angles of the sun during the winter, solar hot water heaters in Minnesota are
rarely able to meet a home’s full needs, so a traditional natural gas or electric hot
water heater is usually needed.


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